FIGS. 1 and 2 are exploded and assembled perspective views, respectively, of a case structure for a flash memory card disclosed in Taiwanese Patent Publication No. 545656. As shown, the flash memory card case structure includes a base 3 and a cover 4. A groove 31 is formed along a periphery of the base 3. A plurality of retaining holes 32 is formed on an inner bottom of the groove 31 at predetermined intervals. Each of the retaining holes 32 includes an inward tapered upper hole 321 and a lower locating hole 322. A plurality of latch plates 41 are formed along a periphery of the cover 4 corresponding to the retaining holes 32 of the base 3. Each of the latch plates 41 has two laterally opposite L-shaped hooking legs 412 with a narrow space 411 existed between them. A curved section 413 is formed on an outer side of each of the hooking legs 412. Being guided by the curved sections 413, the hooking legs 412 of the latch plates 41 can be easily extended through the tapered upper holes 321 into the lower locating holes 322 of the retaining holes 32 and be held therein, so that the cover 4 is connected to the base 3 to form an integral case structure. However, in practice, the above-described structure has some defects as follows:
First, the hooking legs are made of a metal material while the base is made of a plastic material, which has a relatively weak mechanical strength compared to the metal material. Therefore, the plastic retaining holes tend to become worn out and even broken if an end user frequently inserts and extracts the metal hooking legs into and from the plastic retaining holes.
Second, since the cover is connected to the base via engagement of the hooking legs with the retaining holes in two directions in the same plane, the case structure is apt to break apart when it is carelessly dropped or subjected to a sideward impact.
Third, after the latch plates 41 of the cover 4 are inserted into the retaining holes 32 of the base 3, it is uneasy to extract the latch plates 41 from the retaining holes 32. In the event the latch plates 41 are forcedly extracted from the retaining holes 32, the lower locating holes 322 in the plastic groove 31 would become damaged. Therefore, the case structure of FIGS. 1 and 2 does not allow examination and repair of a half-finished electronic product.
FIG. 3 is an exploded perspective view of a case structure for a memory card receiving device disclosed in Taiwanese Patent Publication No. 549688. The memory card receiving device includes a rectangular intermediate frame 60, a top panel 61 connected to a top of the intermediate frame 60, and a bottom panel 62 connected to a bottom of the intermediate frame 60. A wall portion 601 is formed on each of four sides of the intermediate frame 60. A plurality of insertion slots 602 are formed on an inner side of each wall section 601. A plurality of complementary male and female latch plates 611, 612 are spaced along a periphery of the top panel 61 corresponding to the insertion slots 602. Also, a plurality of complementary male and female latch plates 621, 622 are spaced along a periphery of the bottom panel 62 corresponding to the insertion slots 602. When the top panel 61 and the bottom panel 62 are connected to the top and the bottom of the intermediate frame 60, respectively, with the latch plates inserted into the insertion slots 602, the male latch plates 611 and 621 are engaged with the female latch plates 622 and 612, respectively, in the insertion slots 602. The above-structured male and female latch plates have low binding strength. Therefore, the top panel 61 and the bottom panel 62 are not firmly locked to one another in the intermediate frame 60.
FIG. 4 is an exploded perspective view of a conventional memory card case structure including an intermediate frame 70, a first cover 71, and a second cover 72. A plurality of insertion slots 702 are spaced along the intermediate frame 70 to extend in a thickness direction of the intermediate frame 70. A plurality of male and female latch plates 711, 712 is spaced along a periphery of the first cover 71. Also, a plurality of complementary female and male latch plates 722, 721 is spaced along a periphery of the second cover 72. When the first and second covers 71, 72 are connected to two opposite sides of the intermediate frame 70, the male and female latch plates 711, 721, 712, 722 are extended into the insertion slots 702 with the male latch plates 711 and 721 engaged with the female latch plates 722 and 712, respectively. In practice, the above-described structure has some shortcomings as follows:
First, the latch plates have complicated configurations and therefore require complicated punching dies to manufacture the first and the second cover 71, 72. As a result, the memory card case structure requires higher designing and manufacturing costs and longer manufacturing time to adversely affect the product development.
Second, the latch plates have complicated configurations and require high accuracy to enable correct assembly of the half-finished and finished products with a tolerance less than 0.10 mm. This leads to increased manufacturing cost and has adverse influence on the competition ability of the products in the market.
It is therefore tried by the inventor to develop a case structure for card-type electronic product to eliminate the drawbacks in the conventional similar products.